Method of producing nitro-biphenyls and nitro-terphenyls



3,403,185 METHOD OF PRODUCING NITRO-BIPHENYLS AND NITRO-TERPHENYLS John Martin Nilsson, Solna, and James Axel Christer Bjiirklund, Stockholm, Sweden, assignors to Aktiebolaget Bofors, Bofors, Sweden, a corporation of Sweden No Drawing. Filed Nov. 30, 1966, Ser. No. 597,845 Claims priority, applirgation Sgveden, Dec. 9, 1965,

7 Claims. c1. 260-612) Biphenyls have generally been produced by means of the so-called Ullman biaryl synthesis (1). This is primarily suitable for producing symmetrical biphenyls.

The metallic copper acts as a reactant to combine with the halogen (iodine) atoms as the rings are joined to form biphenyl.

In attempts to produce unsymmetrical biphenyls, mixtures of symmetrical and unsymmetrical biphenyls are obtained, in varying proportions, e.g.:

This results in not only low yields of unsymmetrical biphenyls, but difiiculties in isolating them, as the different biphenyls often have similar physical properties.

The present invention relates to a novel method which can be applied with a good yield to produce unsymmetrical biphenyls, with formation of only negligible quantities of symmetrical biphenyls during the reaction, and during which reaction the production of terphenyls may also be accomplished. In particular, the novel method of this invention is useful in preparing nitro-biphenyls and nitroterphenyls. This novel method is based upon the use of copper (I) oxide instead of metallic copper for the reaction, and comprises heating aromatic activated halogen compounds, e.g., iodine compounds, with aromatic nitro compounds and copper (I) oxide, in the presence of a solvent such as quinoline to form desired unsymmetrical biphenyls.

In the present invention, the high reactivity of aromatic nitro compounds is utilized. 2-nitro-benzoic acid, when heated with copper (I) oxide in suitable solvent, produces a rapid evolution of carbon dioxide and the formation of nitro-benzene. If aromatic iodine compounds or other reactive aromatic halogen compounds are present, these react rapidly with the decomposing Z-nitro-benzoic acid, to form unsymmetrical biphenyls according to Reaction Scheme 3 below. Only negligible quantities of symmetrical biphenyls are then formed. In the reaction, anhynited States Patent ice d'rides of the acids can also be used, although this does not result in any further advantage.

ITIO; OCH3 @0001 +1 w.

N02 0on3 @Q 002 CuI wmo Aromatic nitrocompounds, particularly 1,3-dinitro-benzene and its derivatives, react in the same way to give biphenyls according to foregoing Reaction Scheme 4.

Compounds such as 1,3,S-trinitro-benzene can be adlowcd to react with 2 mols of the aromatic halogen compound to give m-terphenyls (Reaction Scheme 5).

( lIl z OzNQ 2r oom 01120 OCH:

ornoQ -No, 2CuI H20 N02 ?CH3 N02 1 l N02 OCH; N0:

OCH3

1G4 We The nitro-biphenyls and nitro-terphenyls produced according to this method are important and valuable intermediates for the syntheses of amines, dyestufis, pharmaceuticals, etc.

The following examples illustrate the invention.

.3. EXAMPLE 1 2-nitro-2'-methoxybiphenyl A mixture of 2-nitr0-benz0ic acid (8.2 g.), 1-iodo-2- methoxy benzene (11.7 g.), copper (I) oxide (4.5 g.) and quinoline (25 ml.) is refluxed for 15 minutes at 240 C. A violent reaction takes place, and water and carbon dioxide are evolved. The mixture is allowed to cool, approximately, 300 ml. of ether is added, and the precipitate formed, which contains, among other things, copper (I) iodide, is filtered off and washed with ether. The quinoline is removed from the filtrate by extraction with diluted hydrochloric acid, and the filtrate washed with water and dried. After the ether has 'been distilled off, an oil is obtained which on vacuum distillation gives 2-nitro-2-methoxybiphenyl (5.1 g. 50% yield, melting point 80-83 C.).

EXAMPLE 2 2-nitro-4'-methoxy-biphenyl The reaction of Z-nitro-benzoic acid anhydride (7.9 g.), 1-iodo-4-methoxy benzene (11.7 g.), copper (I) oxide (4.5 g.) in quinoline (25 ml.) for 15 minutes at 240 C., is carried out as in Example 1 to give 2-nitro-4-methoxy biphenyl (32% yield, melting point 6164 C.).

EXAMPLE 3 2,2-dinitro-biphenyl The reaction of 2-nitrobenzoie acid (8.2 g.), 2-chloronitro-benzene (8.7 g.) or 2-bromo-nitro-benzene (10.1 g.), copper (I) oxide (4.5 g.) in quinoline (25 ml.) for 15 minutes at 240 C. is carried out as in Example 1 to give 2,2-dinitr biphenyl (3035% yield, melting point 121123 C.).

EXAMPLE 4 2,4-dinitro-biphenyl Reaction of 2,4-dinitro-benzoic acid (11.4 g.), iodobenzene (10.2 g.), copper (I) oxide (45 g.) and quinoline (25 ml.) for 15 minutes is carried out as in Example 1 to give 2,4-dinitro-biphenyl (15% yield, melting point 107-1 10 C.) and small quantities of 2,6-dinitro-biphenyl.

EXAMPLE 5 2,6-dinitro-4'-methoxy-biphenyl Reaction of 2,6-dinitro-benzoic acid (11.4 g.), l-iodo- 4-methoxy benzene (11.7 g.), copper (I) oxide (4.5 g.) and quinoline (125 ml.) for 12.5 minutes at 240 C. is carried out as in Example 1 to give 2,6-dinitro-4-methoxy biphenyl (31% yield, melting point 113116 C.).

EXAMPLE 6 2, 6-dinitro-3 ',4'-dimethoxy-bipheny1 A mixture of 1,3-dinitro-benzene (8.4 g.), 1-iodo-3,4-dimethoxy-benzene (13.2 g.), copper (I) oxide (4.5 g.) and quinoline (125 ml.) is refluxed for 2 hours. After cooling, the mixture is treated as in Example 1 to give 2,6-dinitro- 3',4'-dimethoxy-biphenyl (58%, melting point 130- 13 1 C.)

.4. EX M 7 I 2-nitro-2'-riiethoxy biphenyl A mixture of nitro-benzene (6.2 g.), 1-iodo-2-methoxybenzene (11.7 g.), copper, v(I) oxide (4.5 g.) and quinoline is refluxed for l0hours. After cooling, the mixture is treated as in Example 1, to give 2-nitro-2'-methoxy-biphenyl (6% yield, melting "p0int80-83" C.).

EXAMPLE 8 4-metl1oxy-2,4,6'-trinitro-biphenyl and 4,4"-dimethoxy 2',4",6 trinitro-m-terphenyl 2',5-dimethoxy-2,2",6,6"-tetranitro-p-terphenyl A mixture of 1,3-dinitro-benzene (3.36 g.), 1,4-di-iodo- 2,5-dimethoxy-benzene (3.90 g.), copper (I) oxide (215 g.) and quinoline (25 ml.) is refluxed for 5 hours. After cooling, the mixture is treated as in Example 1, to give the sparingly soluble 2,5'-dimethoxy-2,2,6,6-tetranitro-pterphenyl (12%, melting point} 341343 C.).

We claim:

1. A method of producing nitro-biphenyls or nitroterphenyls which comprises heating in quinoline an aromatic nitro compound selected from the group consisting of nitro-benzene, 1,3-dinitro-benzene, 1,3,5-trinitro-benzene, Z-nitro-benzoic acid, 2,4-dinitro-benzoic acid, 2,6- dinitro-benzoic acid, and the anhydrides'of. saidacids, a halogen substituted benzene selected from the group consisting of iodobenzenes, nitro-chloro-benzenes, and nitrobromo-benzenes, and copper (I) oxide.

2. A method according to claim 1, wherein the halogen substituted benzene is a monohalogen compound.

3. A method according to claim 2, wherein the monohalogen compoundis a mono-iodo compound.

4. A method for producing nitro-terphenyls in accordance with claim 1, wherein the halogen substituted benzene is a di-halogen compound.

5. A method in accordance with claim 4, wherein the di-halogen compound is a di-iodo, compound.

6. A method for producing nitro-m-terphenyls in accordance with claim 1, wherein the aromatic nitro compound is 1,3,5-trinitro-'benzene.

7. A method in accordance with claim 6, wherein the halogen substituted benzene is a mono-iodo compound.

.R mr i e BERNARD HELFIN, Primary Examiner. 

1. A METHOD OF PRODUCING NITRO-BIPHENYLS OR NITROTERPHENYLS WHICH COMPRISES HEATING IN QUINOLINE AN AROMATIC NITRO COMPOUND SELECTED FROM THE GROUP CONSISTING OF NITRO-BENZENE, 1,3-DINITRO-BENZENE. 1,3,5-TRINITRO-BENZENE, 2-NITRO-BENZOIC ACID 2,4-DINITRO-BENZOIC ACID, 2,6DINITRO--BENZOIC ACID, AND THE ANHYDRIDES OF SAID ACIDS, A HALOGEN SUBSTITUTED BENZENE SELECTED FROM THE GROUPS CONSISTING OF IODOBENZENES, NITRO-CHLORO-BENZENES, AND NITROBROMO-BENZENES, AND COPPER (I) OXIDE. 